On Offer: 0.472 gram end piece of Erg Atouila 001 Achondrite-ung

Official Name: Erg Atouila 001

Abbreviation: EA 001

Classification: Achondrite Ungrouped - this is a truly unique ungrouped potassium rich meteorite from an unknown differentiated parent body. Composed almost entirely of albitic plagioclase, it's oxygen isotope profile " plot near the acapulcoite-lodranite field" according to the classification, however there is no petrologic affinity to this group as its modal composition is nothing like these primitive achondrites, but rather closer to a particular type of ureilite known as a "trachyte".

Thus the ungrouped classification, as it doesn't fall into any existing taxonomical meteorite group. This is among the most interesting and unique of the newly emerging ungrouped achondrites. These types of achondrites are helping us understand the dynamics of early accretion and solar system formation and at times forcing us to adjust well establish chronologies and models.

These particular specimens show significant shock darkening, and the occasional small olive green phenocryst as well as bright kamacite (metal) blebs. The large grain size described in the classification can easily be seen in these specimens. We only have a few grams of this material. These piece that these slices and end cuts were made from was sent to us directly from Mr. Aide, the main mass holder.

Year found: 2020

Country: Mali

Description: End piece of an amazing ungrouped achondritic meteorite with official name Erg Atouila 001.

What you get: 0.472 gram Erg Atouila 001 specimen as shown, shipping/storage membrane box, and signed Certificate of Authenticity.

We offer a 100% no questions asked 30 day return policy.

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Erg Atouila 001

Basic information

Name: Erg Atouila 001
This is an OFFICIAL meteorite name.
Abbreviation: EA 001
Observed fall: No
Year found: 2020
Country: Mali
Mass: 793 g

Classification
history:

Recommended:

Achondrite-ung [explanation]

This is 1 of 131 approved meteorites classified as Achondrite-ung. [show all]
Search for other: Achondrites, Ungrouped achondrites

Comments:

Approved 19 Dec 2021

Writeup

Writeup from MB 110:

Erg Atouila 001 (EA 001) 22.489944, -4.551744

Gao, Mali

Find: 2020

Classification: Ungrouped achondrite

History: The first piece of 553 g was found by a nomad in August 2020. A second piece of 240 g was found less than a km from the first piece location in September 2020. Both pieces were purchased by Mohamed Aid.

Physical characteristics: Two similar appearing pieces, 553 and 240 g. Exterior is dominated by a pink to light orange color with some dark gray patches with oxidation halos, and some small green patches are scattered throughout. No fusion crust is present. Several dark-colored shock melt veinlets are visible.

Petrography: (M. Spilde, A. Ross, C. Agee, UNM) Microprobe examination and an SEM survey show that albitic alkali feldspar makes up 95% of the modal abundance of this meteorite. Clinopyroxene makes up approximately 3% of the mode, phases with less than 1% modal abundance include olivine, K-feldspar, fluorapatite, troilite, Fe-metal, ilmenite, and oxidized iron. Small poikiolitic inclusions of olivine and lamellae of K-spar are ubiquitous within the host albite. Clinopyroxene occurs primarily in centimeter-sized nodules along with olivine inclusions and other minor phases.

Geochemistry: (A. Ross, UNM) Albite Ab_91.8±0.7Or_6.3±1.1An_1.9±0.4, n=4; K-feldspar Ab_10.2±2.3Or_89.3±2.4An_0.5±0.1, n=3; high-Ca pyroxene Fs_10.0±0.6Wo_44.0±0.4, Fe/Mn=9±1, n=10; olivine Fa_29.3±0.8, Fe/Mn=20±1, n=3; apatite F=3.2 wt%, Cl=0.13 wt%, iron metal Ni=0.26±0.02 wt%, n=3. Oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave δ¹⁸O= 4.789, 4.744, 4.088; δ¹⁷O= 1.437, 1.423, 1.074; Δ¹⁷O= -1.091, -1.082, -1.084 (linearized, all per mil, TFL slope=0.528).

Classification: Ungrouped achondrite (albitite). This meteorite is an albitite with one of the highest modal feldspar contents ever reported in a meteorite – comparable modal abundance to lunar anorthosite meteorites, however its feldspar is an alkali feldspar solid solution. This albitite meteorite is also unlike other Na-feldspar-rich ungrouped achondrites such as GRA 06128/06129 (Shearer et al., 2008) and Almahata Sitta ALMA-A (Bischoff et al., 2014) which have feldspar as plagioclase solid solutions. When plotted on a total alkali-silica (TAS) diagram the bulk composition of this meteorite falls within the trachyte field. Given the relatively coarse grain size present, syenite or olivine syenite are alternative igneous rock names for this meteorite. The oxygen isotope values plot near the acapulcoite-lodranite field although there is no obvious petrologic link between this meteorite and acapulcoites/lodranites.

Specimens: 20.5 g on deposit at UNM, Mohamed Aid holds the main mass.

Bibliography:

Bischoff A., Horstmann M., Barrat J.-A., Chaussidon M., Pack A., Herwartz D., Ward D., Vollmer C. and Decker S. (2014) Trachyandesitic volcanism in the early Solar System. Proceedings of the National Academy of Sciences 111, 12689–12692. (link)
Shearer C. K., Burger P. V., Neal C. R., Sharp Z., Borg L. E., Spivak-Birndorf L., Wadhwa M., Papike J. J., Karner J. M., Gaffney A. M., Shafer J., Weiss B. P., Geissman J. and Fernandes V. A. (2008) A unique glimpse into asteroidal melting processes in the early solar system from the Graves Nunatak 06128/06129 achondrites. American Mineralogist 93, 1937–1940. (link)

Data from:
  MB110
  Table 0
  Line 0:

State/Prov/County:	Gao
Place of purchase:	Mali
Date:	2020
Latitude:	22.489944
Longitude:	-4.551744
Mass (g):	793
Pieces:	2
Class:	Achondrite-ung
Shock stage:	high
Weathering grade:	moderate
Fayalite (mol%):	29.3±0.8
Ferrosilite (mol%):	10.0±0.6
Wollastonite (mol%):	44.0±0.4
Classifier:	C. Agee, UNM
Type spec mass (g):	20.5
Type spec location:	UNM
Main mass:	Mohamed Aid
Comments:	Fieldname AID-235; submitted by C. Agee

Plots:

O isotopes: